The ESRB has released a rating summary for the first EA Sports to receive an M (for Mature rating, Fight Night Champion. The game got tagged with the following content descriptors: Blood, Strong Language, Suggestive Themes and Violence. You can view the full rating summary below:

This is a boxing simulation game in which players can fight boxers from the past and present in regulation-style matches. Players follow the standard rules of boxing as they hit opponents with a series of head and upper-body shots. Knockout punches are replayed in slow motion, with crunching sounds and skin-rippling effects; repeated punches can draw splashes of blood on players' face, chest and shorts. During one cutscene, a brawl breaks out in which large amounts of blood are splattered across a character's body and the floor. Ring card girls are depicted in tight clothing or bikinis, and the camera occasionally lingers on their chest or buttocks; players can also choose tattoos for their character—a handful depict women in revealing outfits. The words "f**k," "a*s," and "sh*t" can be heard in the dialogue.